There was a flurry of interest in Groupon's stock just before the IPO, driving up the price a bit. But Wall Street's crush on the online discounter was short-lived: Its stock plummeted today, for the second time in a month. Maybe reason will actually prevail in tech investing, just this once.

Groupon is back to its original, debut price of $20 per share after a fall of 15 percent today. It sounds like early buyers are flipping their (often discounted) shares and getting out the stock; the New York Times notes that "there are already signs of flight from large institutional investors, who may be cooling on the new class of Internet companies." The other freshly public tech company, LinkedIn, has also been suffering. It looks like the irrational exuberance of the current tech bubble won't really spread to the public markets until Facebook goes public next year. Let's all give thanks for that.